The present invention relates generally to radio frequency identification (RFID) systems and devices. More particularly, the present disclosure relates to systems and devices for further confining and focusing radio frequency energy when applied with the use of RFID transponders that are moving in high speed linear motion through use of a conveyance to allow for the singulation of carton contents.
Radio frequency identification (RFID) tags are electronic devices that may be affixed to items whose presence is to be detected and/or monitored. The presence of an RFID tag, and therefore the presence of the item to which the RFID tag is affixed, may be checked and monitored by devices known as “readers” or “reader panels.” Readers typically transmit radio frequency signals to which the RFID tags respond. Each RFID tag can store a unique identification number. The RFID tags respond to reader-transmitted signals by providing their identification number and additional information stored on the RFID tag based on a reader command to enable the reader to determine identification and characteristics of an item.
Currently, the need for the ability to scan RFID transponders in automated environments has caused the creation of a scanning tunnel or enclosure (i.e., a RFID dynamic tunnel scanner). Different manufacturers may take different approaches to scanning these transponders. Typically, an enclosure uses a combination of absorber material to attenuate radio frequency energy and a read chamber central to the enclosure that projects a read zone. Thus, the read chamber uses an absorber method that directs the main flow of energy normal to the antenna plain, creating the read zone. However, although this does create a field or read zone, it does not allow for tuning of the read zone. Refinement (or tuning) of the leading edge signal of the read zone is critical to the success of reducing the overall gap or spacing required between cartons. Further, some degree of tuning can be done by means of power modulation to the antenna contained within the read chamber. However, this is only marginally effective as a function of the power decreases so does the effectiveness of the reader to energize the transponders.
Furthermore, the main challenge in utilizing a RFID dynamic tunnel scanner is the inability to capture all of the inlay/transponders applied to each individual item within a given carton. Specifically, spacing between cartons, speed of the conveyor equipment, power supplied by the RFID reader, among other parameters are all very difficult to manage to achieve a 100% read rate without creating over-read conditions whereby inlays from adjacent cartons upstream or downstream of the intended carton are read as well. The other end of the spectrum of course is not reading all of the tags properly. Typically, this is overcome by lowering power or tuning the solution to a specific inlay type. This can be done by filtering software data and using a probability model to take a “best guess” as to the completeness of a particular carton. This method may be acceptable to some end users but is limited as it assumes a level of inaccuracy, as it is based on a best guess of the volume of information fed to the model.
Another way to overcome this problem is tuning to a specific power setting for a particular inlay. However, this method may not work if the user utilizes multiple inlay types across their product portfolio. This use of multiple inlay types sets up a scanning requirement where potentially both high and low sensitivity tags are in use. In a manufacturing environment, it is common to use a single inlay as there is consistent product. However, in a distribution environment any number of carton sizes and item types can be moved through the system. This larger variety of product will most likely have a variety of two or more different inlay types. Thus, RFID dynamic scanning requires adaptability.
Another method is software filtering. This method of filtering may not work, because it does not preclude the reading of extraneous inlays that happen to be nearby. Thus, the system is forced to make a judgment whether or not to include the inlay or inlays that happen to be seen in the field as part of a carton count. As a result, intended inlays may not be included. Accordingly, this method depends exclusively on the software for “accuracy” verses a well-designed tunnel that provides superior isolation.
The present invention discloses a RFID dynamic tunnel scanner, which doesn't depend on software for accurate reads. Instead, the RFID dynamic tunnel scanner relies on the physics of carefully manipulated radio frequency energy. Further, the proposed RFID dynamic tunnel scanner provides adaptability to changing conditions in real-time, thus providing a greater ability of handling a large variety of inlay challenges now, as well as in the future.